Recently it was reported that individuals with intermediate or high aryl hydrocarbon hydroxylase (AHH) inducibility are more susceptible to lung cancer than those with low inducibility. Furthermore it was reported that AHH inducibility was inherited as a single gene with codominant expression of alleles. The ability to identify individuals who have a high risk of lung cancer due to a common genetic polymorphism has great significance for cancer control and prevention. Due to the importance of the mode of inheritance of AHH inducibility, we propose to repeat the original observations with a much improved assay we developed which is 20-fold more sensitive and much more reproducible. We will also look for linkage of AHH inducibility with other common genetic polymorphisms and screen for genetic polymorphisms of other enzymes that metabolize carcinogens.